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Re: More green water

> OK I may not have all the facts about exactly but I do know that the
> dried bacteria worked.  I may be wrong but the correlation seemed to be
> very strong.


I can see a basis for your observation.

Nitrifing bacteria compete with plants and other organisms for ammonia. 
The nitrifiers oxidize ammonia for energy and algae and plants use it to
provide nitrogen for essential amino acids and other nitrogen-containing
molecules.  Most can also use nitrate as a nitrogen source, but that 
requires more chemical energy.  If nitrification is suppressed (e.g. by
antibiotics) then the green water algae can grow with reduced competition
- at least for ammonia.  Adding the bacterial culture could increase their
activity, decrease the ammonia availability and end the green water bloom. 

I think I can say that with some basis in experience.  I previously
mentioned seasonal green water blooms in my sunlit, unfiltered tanks. 
They have been sunlit for about 6 years, but unfiltered for only about 2
years.  The green water blooms never happened before I turned off the
filters.  I have always attributed the change to the decrease in
nitrifying activity brought on by removing the filters. 

Conditions where adding nitrifying bacteria will control a green water
bloom (or where removing a filter will cause one) may be fairly rare. 
Either of those occurences requires that all other contributing factors
must be poised so that the seemingly small difference in the nitrogen
source (ammonia .vs.  nitrate) can control the success of the algae.

Roger Miller